Abstract: The PnP problem is a classical problem in computer vision and photogrammetry，and is widely used for camera pose determination.The paper discusses the solutions of P3P problem under certain conditions，and gains some distinct conclusions with other literatures.The result presented in this paper appears instructive for both theoretical and practical points of view.

Key words: transformation-based definition, depth-ratio, multiple solutions

摘要： PnP问题是计算机视觉与摄影测量学中经典而重要的问题之一，在姿态定位中应用广泛。结合已有的研究成果，利用韦达定理对P3P问题多解的现象进行详细地研究，并给出了一些判定条件，从而扩展了P3P问题多解的判别条件的适用范围。研究结果对实际的摄像机定位具有一定的理论和应用价值。

关键词: 基于变换定义, 深度因子, 多解现象